a bit about algae - watersheds

A bit about Algae

Bev ClarkLake Partner ProgramDorset Environmental Science Center

Algae

• small, mostly microscopic plants• live in virtually all water bodies• free floating, some attached• thousands of species• many different habitats and habits• similar to other terrestrial plants in that

- they require nutrients, light, - grow better when it’s warm etc.

Generally algae are important- good for the lake- necessary part of ecosystem integrity- responsible for the atmosphere

What’s good about algae?

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Presentation Notes�

Algae are primary producers. These use sunlight and nutrients to grow and they are used as food for zooplankton which are in turn eaten by fish. Algae are an important part of the lake ecosystem�

What about ‘bad’ algae? What about algal blooms?

total phosphorus (ug/L)

0 10 20

Algal Blooms• taste and odour problems• oxygen depletion• toxin production (blue green algae)

total phosphorus (ug/L)0 10

Canadian Shield- typically oligotrophic

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Most lakes on the Canadian Shield are oligotrophic which means that they have low total phosphorus concentrations (<10ug/L) and they rarely experience algal blooms.�

Not as many lakes off the shield

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Algae are undesirable when nuisance growth or blooms occur. Algal blooms reduce water clarity, can cause taste and odour problems with drinking water, can reduce oxygen levels in the lake and can, in the case of the blue green algae, produce harmful toxins.�

Which is why we don’t have many algal blooms in Ontario

(except in 2007)

A few lakes bloom every year, some bloom frequently (nuisance)These are usually high nutrient lakes i.e. > 20-30 ug/L (eutrophic systems)

Rice Lake

Brandy Lake

Lake of the Woods

Others:Lake ErieBay of Quintemany urban Lakes

Troy Lake

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Some lakes bloom almost every year and these are usually eutrophic lakes with more than 20ug/L total phosphorus. Relatively speaking there are not very many of these lakes in Ontario�

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They are mostly off the Canadian Shield i.e. in the south.�

A few lakes on the Shield bloom intermittently (worse with warmer weather?)

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Some lakes on the shield are more enriched and can occasionally support algal blooms�

Three Mile (15-25 ug/L)

Sturgeon Bay (15-20 ug/L)

Bass Lake (10-20ug/L)

Charleston (10-20ug/L)

most are mesotrophic and shallow (9-11m?)

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Examples of on-shield lakes with blooms – most are mesotrophic 10-20ug/L�

So…most lakes behave as you would expect (until the weather gets weird).

• Planktothrix rubescens• Spring bloom• Little Lake Panache• Fall blooms common• TP 10-20ug/L• short ice cover

• Anabaena• Bagot Long Lake• mean TP = 12.7ug/L• TPso 2007 <10ug/L• also short ice cover• 9 - 11 m deep• internal load

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Weather causes strange algal blooms in lakes which do not normally bloom. Some of these like Bagot Long Lake are low in nutrients. Extra nutrients can come from the bottom of the lake under certain weather conditions like hot summers�

2007

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Some strange blooms look like blue green blooms�

Lake Simcoe - Spirogyra

Simon Lake - hydrodictyon

These look like blue green blooms- But they’re not

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But are often rare algae or algae growing in extreme qualities�

Conjugating Algae- also grow better with hot weather- do not produce toxins- probably not a nuisance in shield lakes

(Spirogyra, Zygnema, Mougeotia)

Oedogonium

Big Hawk

Caribou

Opinicon

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Congugating algae are harmless and more common in warm weather years�

Chrysophytes- low nutrients- shift in algal communitiesthroughout Ontario

Shoe Lake Uroglena bloom - 2007

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Chrysophyte blooms are more common in Ontario than in the past. They can cause taste and odour problems but are not toxic They are more common in warmer weather �

Questions

a bit about algae - watersheds

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